Electron-beam-induced conduction in polyethylene

Abstract

The electrical conduction in polyethylene induced by the irradiation of the short pulsed electron beam (100-nsec time width) consists of the fast and the slow components. The former is attributed to the carrier transport in the crystalline part and the latter to that in the amorphous part. A logarithmic plot (Scher-Montroll plot) of the slow part of the induced current versus time gives a knee at time Tr, which is thought to be the transit time of the carrier front between electrodes. Simple calculation by the formula μ=L/TrE gives the apparent slow carrier mobility μ of 5.6×10−7 and 3.2×10−7 cm2/V sec for the electron and the hole, respectively, at 343 K under a field E of 1.2 MV/cm for sample thickness L of 12 μm. These apparent slow carrier mobilities are dependent on both the thickness and the field strength. These behaviors are discussed in terms of Scher-Montroll theory on transport in amorphous substances. The activation energy of the mobility is in good agreement with the apparent trap depth obtained from the TSC measurement.